::highlight(my-highlight1) {
  background-color: red;
  color: black;
}

::highlight(my-highlight2) {
  background-color: gainsboro;
  color: yellowgreen;
  font-weight: bold;
  text-decoration: underline;
  font-size: 24px;
}

textarea {
  width: 500px;
  height: 200px;
  font-size: 24px;
  font-weight: bold;
}


div.pulsate {
  width: 300px;
  height: 300px;
  border-radius: 50%;
  box-shadow:
    0 0 20px #fff,
    -20px 0 80px #f0f,
    20px 0 80px #0ff,
    inset 0 0 50px #fff,
    inset 50px 0 80px #f0f,
    inset -50px 0 80px #0ff,
    inset 50px 0 300px #f0f,
    inset -50px 0 300px #0ff;
  animation: pulsate 6s linear infinite;
  margin: 100px auto;
}

@keyframes pulsate {
  50% {
    box-shadow:
      0 0 20px #fff,
      20px 0 80px #f0f,
      -20px 0 80px #0ff,
      inset 0 0 50px #fff,
      inset -50px 0 80px #f0f,
      inset 50px 0 80px #0ff,
      inset -50px 0 300px #f0f,
      inset 50px 0 300px #0ff;
  }
}

body {
  background-color: black;
}